trying to gain weight and staying in shape

Options
I have been doing bodypump faithfully 3 times a week for more than 5 years. I Love it!!! Since I am not terribly coordinated, other workouts are not for me. I fall over my own feet. Within a month, my arms became so defined---I am really proud of them. The problem is I am small. 5'2 and I was very underweight. 99lbs. Started logging my food, and really working on eating more. Don't like sweets, and eat a steak maybe once a week. Today I got checked at the fitness center----since last month I now weight 105.5, my bmi went from 17 to 14 and b/p right after the workout was 109/70. Does anyone else here have issues with being to small?